silver currency must undergo certain modifications in order that a definite round number of silver units may be equal to the gold unit, or on the other hand the gold unit must undergo modification. But as we have shown that the gold unit remained unaltered throughout all Hellas, Asia and Egypt down to the time of the Ptolemies, it follows that whatever changes were necessary must have taken place in the _silver_ standards. Of this we have proof in the case of Rhodes itself. Down to 408 B.C. the three ancient cities of Ialysus, Camirus and Lindus issued each a separate series of coins, Camirus on the Aeginetic standard, the other two on the Phoenician. In 408 B.C. all these united in founding the new city of Rhodes, and henceforward there is a single coinage. At first the Attic standard seems to have been employed for silver, as rare tetradrachms of 260 grs. are found, but it must have very soon given place to the so-called Rhodian, the tetradrachm of which ranges from 240 to 230 grs. About the same time (400 B.C.) the Rhodians began to issue gold staters of the so-called Euboic standard, and for a century this double issue of gold and silver continued unbroken. It is plain, from the case of this famous island, that it is only the silver standards which changed. There can be no doubt that the unit by which gold in bullion was reckoned before that metal was coined was the so-called Euboic or ox-unit, but during the archaic period we find both the so-called Phoenician (220 grs.) and Aeginetic (drachms of 92 grs.) being employed for silver in the island, whilst after 408 B.C. gold is issued on the ox-unit, but silver, although at first on this standard, immediately changes to the Rhodian of 240 grs. Evidently then the fixed element is the gold, the fluctuating the silver. The coinage of Rhodes likewise exemplifies the doctrine already indicated, that the employment of religious and mythological symbols seems to mark not the earlier but rather the later stages of Greek coining. Thus Camirus employed the fig-leaf, Ialysus half a winged boar, and Lindus the lions head with open jaws, but after 408 Helios the Sun-god, from whom all Rhodians alike claimed descent, and to whom the island was sacred[414], becomes the regular type, with the _type parlant_ of the Rose (_Rhodon_) on the reverse.